this returns an error code 11: The signature of the request does not match the request parameters.

I'm using the following endpoint: https://platform.healthvault-ppe.com/platform/wildcat.ashx
Also the redirection url I received after authorizing the app contains the following:
https://<MY_URL>/?gws_rd=cr&ei=h5ewUuKLJa7IsASc4YHIAw I'm not using this parameters, if that helps.

Any hint will be greatly appreciated.

UPDATE: I already checked the HMAC encoding using a third party service and it returned the same as my app